built only with a note, a third
above it, and its perfect fifth
I have always found to be boring. It is too stable.
Called a triad, major if the third is composed of four semitones, and minor if the third is composed of three semitones.
For my own playing--improvisation actually--I prefer the instability of an added seventh above the root, a minor seventh is OK, but a major seventh is far more interesting to my ear.